Electrohydraulic control device for double-acting consumer

Abstract

An electrohydraulic control device ( 10 ) for a double-acting consumer ( 11 ) is proposed, in which a continuous volumetric flow control to and from the consumer ( 11 ) is possible with two proportional 4/2-way magnet valves ( 12, 13 ), each with one seat valve function ( 26 ), and by means of two blocking valves ( 29, 38 ) of the seat valve type; free floating is attainable as the fourth work position. The magnet valves ( 12, 13 ) are structurally identical and are each connected into the volumetric flow to the consumer and the volumetric flow leaving the consumer; each consumer connection ( 28, 36 ) is sealed off tightly by a seat valve function ( 26 ) of the magnet valves ( 12, 13 ) and a blocking valve ( 29, 38 ). The magnet valves ( 12, 13 ) have a main control member ( 57 ) and a pilot control member ( 58 ), which cooperate in the manner of a followup controller and make do without a separate control oil supply, so that high hydraulic capacities can be controlled continuously and with short response times.

What is claimed is:  
     
       1. An electrohydraulic control device for a double-acting consumer, said electrohydraulic control device comprising 
       a first consumer connection ( 28 ) to the double-acting consumer ( 11 ), a second consumer connection ( 36 ) to the double-acting consumer ( 11 ), a first work conduit ( 27 ) communicating with the first consumer connection ( 28 ) and including a first blocking valve ( 29 ) for blocking the first consumer connection ( 28 ), a second work conduit ( 37 ) communicating with the second consumer connection ( 36 ) and including a second blocking valve ( 38 ) for blocking said second consumer connection ( 36 ), a first lowering conduit ( 35 ) communicating with the second consumer connection ( 36 ) and a second lowering conduit ( 41 ) communicating with the first consumer connection ( 28 ), each of said lowering conduits by-passing the blocking valves ( 29 , 38 ); and  
       electromagnetically actuable control means for blocking or connecting at least one of the consumer connections, said control means comprising a first four-way, two-position proportional magnet valve ( 12 ;  120 ) and a second four-way, two-position proportional magnet valve ( 13 ;  120 ) identical to said first four-way, two position proportional magnet valve, wherein each of said magnet valves includes a slidable valve control member provided with control edges ( 67 , 71 ), an inlet connection ( 19 ), a return connection ( 22 ), a first motor connection ( 24 ) alternatively connected to the inlet connection ( 19 ) or the return connection ( 22 ) by operation of the slidable valve member with the control edges ( 67 , 71 ), a second motor connection ( 25 ) and seat valve means ( 26 ) for controlling the second motor connection; and  
       wherein the first motor connection ( 24 ) of the first magnet valve ( 12 ;  120 ) communicates with the first work conduit ( 27 ), the first motor connection ( 24 ) of the second magnet valve ( 13 ;  120 ) communicates with the second work conduit ( 37 ), the second motor connection ( 25 ) of the first magnet valve ( 12 ;  120 ) is connected with the first lowering conduit ( 35 ), the second motor connection ( 25 ) of the second magnet valve ( 13 ; 120 ) is connected with the second lowering conduit ( 41 ), and each of said magnet valves has an initial position ( 17 ) in which said work conduit connected thereto is relieved.  
     
     
       2. The electrohydraulic control device as defined in  claim 1 , wherein for each of the magnet valves the second motor connection ( 25 ) is blocked by the seat valve means ( 26 ) and the inlet connection ( 19 ) is blocked by the slidable valve control member in the initial position ( 17 ) and the slidable valve control member has a work position ( 18 ) in which the inlet connection ( 19 ) communicates with the first motor connection ( 24 ) and the second motor connection ( 25 ) communicates with the return connection ( 22 ). 
     
     
       3. The electrohydraulic control device as defined in  claim 1 , wherein each of the slidable valve control members comprises a longitudinally movable main control member ( 57 ); each of the magnetic valves ( 12 ,  13 ;  120 ) comprises a pilot-controlled valve including the main control member ( 57 ), a proportional magnet ( 14 , 15 ) and a pilot control member ( 58 ,  122 ) actuable by the proportional magnet ( 14 , 15 ) to cooperate with the main control member so as to act as a followup controller; and the seat valve means ( 26 ) includes a main valve cone ( 59 ) disposed on said main control member ( 57 ) for blocking the second motor connection ( 25 ) and is connected in series with a fine-control edge ( 65 ) provided on said main control member ( 57 ) for communication with the return connection and said control edges ( 67 , 71 ) are disposed on said main control member ( 57 ) spatially separated from each other. 
     
     
       4. The electrohydraulic control device as defined in  claim 3 , wherein the main control member ( 57 ) has a thickened end portion having an end face defining an end-face pressure chamber ( 61 ), said end-face pressure chamber adjoining the main control member ( 57 ) so that a pressure in said pressure chamber urges the main control member ( 57 ) in a closing direction; the pilot-controlled valve includes means for relieving the end-face pressure chamber ( 61 ) including a slide edge ( 72 ), a pilot control cone ( 73 ) connected in series with the slide edge ( 72 ), said slide edge and said pilot control cone being provided on the pilot control member ( 58 ), and a spring ( 16 ) arranged to urge the pilot control member ( 58 ) in a direction opposite to another direction of motion of the pilot control member caused by operation of the proportional magnet ( 14 , 15 ); and the main control member ( 57 ) has at least one differential face ( 63 ) and said main control member ( 57 ) is urged in an opening direction by a pressure at the second motor connection ( 25 ) acting on the at least one differential face ( 63 ). 
     
     
       5. The electrohydraulic control device as defined in  claim 4 , wherein the main control member ( 57 ) has a second differential face ( 69 ) and is positionable so that a pressure at said inlet connection ( 19 ) acts on said second differential face ( 69 ) urging the main control member ( 57 ) in an opening direction and the pilot-controlled valve includes means for connecting the end-face pressure chamber ( 61 ) with the second motor connection ( 25 ) or the inlet connection ( 19 ) so that the end-face pressure chamber ( 61 ) is selectively acted on by a higher pressure at the second motor connection ( 25 ) or the inlet connection ( 19 ), and the means for connecting includes check valves ( 75 , 76 ) and inlet throttles ( 79 ). 
     
     
       6. The electrohydraulic control device as defined in  claim 3 , wherein the pilot-controlled valve is provided with a slide bore ( 51 ) for the main control member ( 57 ) and said slide bore ( 51 ) includes an inlet chamber ( 52 ), a first motor chamber ( 53 ), a return chamber ( 54 ), an intermediate chamber ( 55 ) and a second motor chamber ( 56 ) arranged in succession spaced from each other along said slide bore ( 51 ) with said inlet chamber ( 52 ) being closest to said proportional magnet ( 14 , 15 ) and said second motor chamber ( 56 ) being furthest from said proportional magnet ( 14 , 15 ), and said connections ( 19 ,  22 ,  24  and  25 ) are assigned to respective ones of said chambers of said slide bore. 
     
     
       7. The electrohydraulic control device as defined in  claim 3 , wherein the pilot-controlled valve has a housing and is provided with a slide bore ( 123 ) through which said main control member ( 121 ) moves, said slide bore including a return chamber ( 128 ), a second motor chamber ( 126 ), a first motor chamber ( 125 ), an inlet chamber ( 124 ) and a magnetic-end pressure chamber ( 143 ) arranged in succession with the magnet-end pressure chamber ( 143 ) closest to the proportional magnet ( 14 , 15 ) and the return chamber ( 128 ) furthest from the proportional magnet ( 14 , 15 ); the main valve cone ( 131 ) controls communication with the return chamber ( 128 ); a spring ( 146 ) is provided in the return chamber ( 128 ) and is arranged to urge the main control member ( 121 ) towards the initial position and to press the main valve cone ( 131 ) against a valve seat ( 129 ) fixed in the housing of the pilot-controlled valve; the magnet-end pressure chamber ( 143 ) is bounded by an end of the main control member ( 121 ) closest to said proportional magnet ( 14 , 15 ) so that a pressure in the magnet-end pressure chamber ( 143 ) urges the main control member ( 121 ) in a direction toward a work position ( 18 ) against action of said spring ( 146 ); said magnetic-end pressure chamber ( 143 ) is connected to the return connection ( 22 ) via a throttle bore ( 144 ) and is connected with the return connection ( 22 ) by means of the pilot control member ( 122 ) and the proportional magnet ( 14 , 15 ) is provided with an armature ( 59 ) and another spring ( 147 ) braced against the housing and holding the pilot control member ( 122 ) against the armature ( 59 ) of the proportional magnet ( 14 ). 
     
     
       8. The electrohydraulic control device as defined in  claim 7 , wherein the main control member ( 121 ) is provided with a throttle bore ( 144 ) and a damping piston ( 145 ) guided slidably in the throttle bore ( 144 ), protruding into the return chamber ( 128 ) and provided with a return throttle. 
     
     
       9. The electrohydraulic control device as defined in  claim 7 , wherein the first motor chamber ( 125 ) is arranged side-by-side of the second motor chamber ( 126 ), the inlet chamber ( 124 ) is located between the first motor chamber ( 125 ) and the proportional magnet ( 140 ) and an intermediate chamber ( 127 ) is located between the second motor chamber ( 126 ) and the return chamber ( 128 ). 
     
     
       10. The electrohydraulic control device as defined in  claim 1 , wherein said two blocking valves ( 29 ,  38 ) each have an inlet-side inlet ( 31 ), a spring-loaded back end, a control connection ( 33 ) communicating with the spring-loaded back end and means for transmitting a pressure prevailing at the inlet-side inlet ( 31 ) of one of the two blocking valves to the control connection ( 33 ) of another of the two blocking valves and thus to the spring-loaded back end thereof so as to block said another of the two blocking valves. 
     
     
       11. The electrohydraulic control device as defined in  claim 10 , wherein each of the blocking valves ( 29 , 38 ) is provided with a throttle check valve ( 84 , 85 ) and the control connections ( 33 ) of both of said blocking valves ( 29 , 38 ) are connected with each other via a blocking valve control line ( 82 ) so that said pressure prevailing at the inlet-side inlet of said one of said two blocking valves is transmitted through said one of said two blocking valves via said throttle check valve and through said blocking valve control line to said another of the two blocking valves. 
     
     
       12. The electrohydraulic control device as defined in  claim 11 , wherein each of said blocking valves includes a blocking piston ( 93 ) with a bolt-like extension ( 92 ), a tubular valve body ( 91 ) guided slidingly on the bolt-like extension ( 92 ) of the blocking piston ( 93 ) and a blocking valve spring ( 94 ) braced between the blocking piston ( 93 ) and the tubular valve body ( 91 ); the blocking piston ( 93 ) and the valve body ( 91 ) have substantially equal outer diameters; a valve passage ( 99 ) extends through each of said blocking valves and said throttle check valve ( 84 , 85 ) is provided in said valve passage ( 99 ). 
     
     
       13. The electrohydraulic control device as defined in  claim 1 , wherein said electromagnetically actuable control means comprises an alternating valve ( 42 ) having a spring-centered middle position and connected between the two first motor connections ( 24 ) of both of the magnet valves ( 12 , 13 ) and said alternating valve ( 42 ) has two opposite end connections ( 44 , 45 ) connected to the respective first motor connections ( 24 ) and a middle connection ( 46 ) connected to a load pressure line so that on pressurizing one of said two end connections ( 44 , 45 ) of the alternating valve ( 42 ) a maximum pressure is transmitted into said load-pressure line. 
     
     
       14. The control device as defined in  claim 13 , wherein said control means has a substantially parallelepiped housing ( 50 ) provided with an end face ( 106 ) and said two magnet valves ( 12 , 13 ) have respective longitudinal axes and are arranged so that said longitudinal axes extend parallel to one another and said proportional magnets ( 14 , 15 ) are arranged on said end face ( 106 ). 
     
     
       15. The control device as defined in  claim 14 , wherein the housing ( 50 ) has an installation face ( 107 ) opposite from said end face ( 106 ) and a cap ( 108 ) covering the installation face ( 107 ), and one of the consumer connections is located in the housing ( 50 ) and another of the consumer connections is located in the cap ( 108 ) and said consumer connections are located on a top side ( 109 ) of the control means. 
     
     
       16. The control device as defined in  claim 15 , wherein a pressure compensating valve ( 105 ) is arranged in the housing ( 50 ) and a pump conduit ( 111 ) extends in the housing ( 50 ) below the two magnet valves ( 12 , 13 ). 
     
     
       17. The control device as defined in  claim 14 , wherein the housing ( 50 ) is provided with valve seats ( 60 ) assigned to main control members ( 57 ) of both of said magnet valves ( 12 , 13 ), axially parallel bores ( 51 , 96 ) open toward an installation face ( 107 ) of the housing on a side opposite from the end face ( 106 ) and additional valve seats for the blocking valves ( 29 , 38 ) arranged in the axial parallel bores ( 51 , 96 ). 
     
     
       18. The control device as defined in  claim 14 , wherein the longitudinal axes of the magnet valves ( 12 , 13 ) are arranged in two longitudinal planes parallel to each other and spaced apart from one another. 
     
     
       19. The control device as defined in  claim 18 , wherein the blocking valves are arranged axially parallel in the housing in different transverse planes, said transverse planes extend spaced apart from each other and parallel to each other and said transverse planes are spaced a distance apart greater than a distance between the longitudinal planes in which the magnet valves are located. 
     
     
       20. The control device as defined in  claim 14 , wherein the two blocking valves ( 29 , 38 ) and the alternating valve ( 42 ) are arranged in the housing ( 50 ) in a region between the two magnet valves ( 12 , 13 ).